1. Field of the Invention
The present invention relates to a test apparatus, a test method, manufacturing method for electronic devices, a test simulator, and a test simulating method. In particular, the present invention relates to a test apparatus, a test method, a manufacturing a method for electronic devices, a test simulator, and a test simulating method, which employ an electric potential comparator having a function of detecting the magnitude correlation between the electric potential difference between a pair of signals forming a differential signal output from a test subject, and a predetermined threshold electric potential.
2. Related Art
There are known conventional test apparatuss for testing the properties of an electronic circuit and so forth. Specifically, with such a test apparatus, an electric potential comparator compares an electric signal output from an electronic circuit which is a test subject with a predetermined threshold voltage. Thus, the test apparatus has a function of determining the acceptability of the electric circuit, and so forth, based on the comparison results. Accordingly, the reliability of the test with such a test apparatus is greatly dependent upon the comparison precision of the electric potential comparator which is a component for making electric-potential comparison. This means that the electronic potential comparator serves as a critical component of the test apparatus from the perspective of reliability and so forth.
On the other hand, a technique using a so-called differential transmission method has been proposed instead of a conventional technique using a single-end transmission method, in order to improve transmission speed, noise-proof property, and so forth. With the differential transmission method, a signal is transmitted via a pair of transmission lines. Specifically, determination is made whether the signal is “High” or “Low” based on the electric potential difference between a pair of electric signals transmitted via a pair of transmission lines. As electronic circuits employing such a differential transmission method is becoming widespread, there is a demand for a test apparatus including an electric potential comparator that supports the differential transmission method in the field of the test apparatuss for testing the properties of the electronic circuits and so forth. Japanese Unexamined Patent Application Publication No. 2002-215712, for example.
However, with conventional test apparatuss and test simulators, even in a case that an electronic device or a device simulator simulating the electronic device outputs multiple output signals, these output signals are tested independent of one another. Accordingly, in a case that there is correlation in the timing at which the multiple output signals change, the electronic device cannot be tested for determining the acceptability thereof, based on this correlation.